My thought would be that it just hasn't been updated, since you wouldn't want anything that is a "negative" pressure. We have chosen the RyMed Invision-Plus Neutral for several reasons. Along with our Clinical Engineering and Infection Control Departments, we tested 11 products on the market and found the RyMed superior in the following ways: It was the ONLY one that was "clean" under blacklight after using a "bug glow" product provided by infection control team, it has one of the smallest priming volumes and dead spaces, it has zero displacement upon connection AND disconnection, it has a straight through pathway and has no special clamping technique to work properly. I wouldn't recommend anything that is "negative" with either connection or disconnection. This is easy to test with microbore tubing and colored water flushing well and connecting/disconnecting the syringe. Our tests showed the RyMed and the BioNector as the only ones that showed zero displacement. Good Luck with your choice. Laura